Squeeze cementing is the process of forcing a cement slurry through holes or splits in a casing/wellbore annular space of a well in order to repair a primary cement job that failed due to the cement bypassing the mud (channeling); to eliminate water intrusion from above, below or within the hydrocarbon-producing zone; to reduce the producing gas to oil ratio by isolating gas zones from adjacent oil intervals; to repair casing leaks due to a corroded or split pipe; to plug all, or part, of one or more zones in a multizone injection well so as to direct the injection into the desired intervals; and to plug and abandon a depleted or watered-out producing zone.
Due to high pressures involved, squeeze cementing is beset with many problems such as propagating fractures. In addition, the use of Portland cement has several potential problems of its own, particularly where high strength and good adhesion to the borehole wall are needed in order to effect good sealing. The presence of drilling mud pockets on channels under the primary cement not only can lead to failure of the primary cement job, but can adversely affect the strength of the squeeze cementing job. In addition, the presence of brine in the well can adversely affect both the primary and remedial cement jobs, increasing setting time and causing loss of strength of the cement.
Accordingly, the present invention is directed to overcoming the above-noted problems with Portland cement used for squeeze cementing.